Netgear WNDR3800 bricked. won't unbrick.

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groupie
DD-WRT Novice


Joined: 09 Aug 2014
Posts: 24

PostPosted: Sun Jul 17, 2016 21:30    Post subject: Netgear WNDR3800 bricked. won't unbrick. Reply with quote
Netgear WNDR3800, had factory firmware, no problems. put latest dd-wrt on it (forgot version, it's gone now anyway) not happy because the DLNA nonfunctional, file sharing semi-functional, and WiFi on/off button on front of the router no longer works. decided to put back to factory firmware.

can't do that with dd-wrt installed. won't take a .img file.

so I used Telnet to connect to the router, logged in, typed "erase Linux" to delete the existing firmware, "reboot" to reboot, and supposedly you can then use TFTP to upload your new firmware.

except it doesn't work.

I can get it to successfully upload, but it's supposed to take a few minutes to write to memory and reboot. never does that, always stays at blinking green light.

tried all different power-up routines to upload the firmware, says successful but then nothing happens.

tried several different TFTP programs in addition to the service that comes with Windows, all do the same thing: successful upload, but router stays at blinking green light and doesn't reboot itself.

tried manually rebooting after 10 minutes. tried reset button at different times. nothing works.

all I have is a blinking green light.

router does everything people say before you upgrade the firmware. power on to solid amber light, then NIC's light up, then blinking green light, etc.

I can do the power-up tricks to make it blink amber 5 times then blink green, etc.

looks and acts like it's ready for firmware upgrade.

does not appear broke.

but the firmware upgrade never does anything.

what can I do?
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mrjcd
DD-WRT Guru


Joined: 31 Jan 2015
Posts: 5339
Location: Texas

PostPosted: Mon Jul 18, 2016 0:29    Post subject: Reply with quote
Probably have to use serial method
but I would first try unbricking method found this page
http://www.dd-wrt.com/wiki/index.php/Netgear_WNDR3800

Have static IP set on your computer
make sure it is in recovery mode -- follow those instructions but ---
instead of using netgear firmware use dd-wrt 26138factory.img found top of that page

If TFTP is successful wait plenty of time then do a power cycle and then try
connect at its default IP or try at last known IP you used on it....make sure computer is set to same subnet if different.

If you get dd-wrt back then follow instructions to revert to netgear firmware.

NOTE: You should always have router set to defaults or 'erase nvram' before you 'erase linux'
especially if going to different type firmware
groupie
DD-WRT Novice


Joined: 09 Aug 2014
Posts: 24

PostPosted: Mon Jul 18, 2016 1:07    Post subject: Reply with quote
did that, exactly from that page. among all the other stuff I tried.

had set dd-wrt to factory defaults before starting any of this

was aware that later than 1.0.0.16 might not work, so tried that at first. (then tried everything else too, dd-wrt and Netgear)

have tried flashing in all sorts of startup modes.

have waited 15 minutes and longer after flashing, never did reboot itself.
groupie
DD-WRT Novice


Joined: 09 Aug 2014
Posts: 24

PostPosted: Mon Jul 18, 2016 2:13    Post subject: Reply with quote
just remembered it's a WNDR3800CH, so I tried using the factory Charter image from

https://www.charter.com/uploads/router-update/WNDR3800-V2.1.0.59CH.img

no dice.

it was originally v1.0.0.61CH, which does not seem to be available anywhere. anybody got a 1.0.0.51CH I can try?

(not the 180 megabyte open source code on support.netgear.com)
KrypteX
DD-WRT Guru


Joined: 18 Jan 2014
Posts: 2411

PostPosted: Mon Jul 18, 2016 6:56    Post subject: Reply with quote
groupie wrote:
just remembered it's a WNDR3800CH, so I tried using the factory Charter image from

https://www.charter.com/uploads/router-update/WNDR3800-V2.1.0.59CH.img

no dice.

Solution: http://www.dd-wrt.com/phpBB2/viewtopic.php?p=1039840#1039840

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groupie
DD-WRT Novice


Joined: 09 Aug 2014
Posts: 24

PostPosted: Mon Jul 18, 2016 15:37    Post subject: Reply with quote
tried both of those image files. didn't work.

with all the different ones I have tried, it's beginning to look like file selection isn't the issue. (although it may still require the right one)

possibilities:
a. wrong procedure
b. board ID header got screwed up and therefore won't take anything?

here is the procedure exactly:

1. set ethernet adapter to
static IP= 192.168.1.10
mask= 255.255.255.0
default gateway= 192.168.1.1

2. get tftp2.exe ready. have these entered:

server: 192.168.1.1
password: admin
file: ...

3. turn on router

amber power light comes on.
then also the 4 amber NIC lights come on.
then those turn off.
then the 1 connected to the computer turns back on.
power light begins blinking green.

4. use tftp2.exe

press "Upgrade" button
power light solid green, amber NIC light stays on
program shows progress bar
got message "Firmware was upgraded successfully!"
power light blinking green

5. wait, the router is supposed to write file to memory (5-10 minutes) and reboot

green light continues blinking.
waited 15 minutes, nothing happens.

6. reboot manually

turn off router.
wait 20 sec.
turn on router.
it has same startup routine as before.
blinking green light.



note, if I use Window's built-in TFTP Client from the command line (instead of the third-party tftp2.exe program) the power light goes off while loading the image. that might mean something. or not.
groupie
DD-WRT Novice


Joined: 09 Aug 2014
Posts: 24

PostPosted: Mon Jul 18, 2016 17:40    Post subject: Reply with quote
there are several different instructions for flashing the firmware. have tried them all. went back to trying this one again:

http://inarea51.com/dd-wrt/builds/wndr3800ch/wndr3800chwebsite/

it says

1. turn off router

2. press reset button for 10 seconds

3. turn on router while still holding down reset button

4. lights will turn on (amber), blink amber a few times, green 10 times, then solid green.

5. use tftp2.exe ...



but this is what happens instead.

4. lights turn on (amber),
then power blinks amber 6 times,
then power is solid green for 1 second,
then power is blinking green. forever.

5. use tftp2.exe (says it was successful) ...
mrjcd
DD-WRT Guru


Joined: 31 Jan 2015
Posts: 5339
Location: Texas

PostPosted: Mon Jul 18, 2016 17:53    Post subject: Reply with quote
I got into same mess with a WNDR3700v4 a while back.
Very frustrating.
Just about to crack open the box but tried TFTP one more time and it worked then.
I'm thinking that was about the 15th attempted using different builds and all said successful but
only that last actually worked....don't even remember which build it was.
.... still not sure why it was being difficult????

I assume you tried TFTP the 'exact' last working firmware you had on it?

good luck -
groupie
DD-WRT Novice


Joined: 09 Aug 2014
Posts: 24

PostPosted: Mon Jul 18, 2016 18:46    Post subject: Reply with quote
the last working firmware was dd-wrt.

the router came with stock Netgear firmware 1.0.0.61CH, I followed the instructions where you put the initial dd-wrt firmware on first then you can put on a better version. did that using the firmwares supplied with the instructions.

but the DLNA was nonfunctional, file sharing was semi-functional, and WiFi on/off button on front of the router didn't work. so I decided to put it back to factory firmware.

couldn't do that with dd-wrt installed because it won't take a .img file.

so I used Telnet to connect to the router, logged in, typed "erase Linux" to delete the existing firmware, "reboot" to reboot, and supposedly you can then use TFTP to upload your new firmware.

except it it's not working.

I can get it to successfully upload, but it's supposed to take a few minutes to write to memory and reboot. never does that, always stays at blinking green light.

I have tried all these firmwares:

Step 1 - factory-to-ddwrt_27506_WNDR3800CH(KrypteX).img
Step 2 - wndr3800-webflash29440(April-11-2016).bin
WNDR3800-V1.0.0.16.img
WNDR3800-V1.0.0.48.img
wndr3800-webflash.bin
WNDR3800-V2.1.0.59CH.img
WNDR3800-V1.0.0.16_forWNDR3800CH.img
WNDR3800CH-V2.1.0.59CH.img
mrjcd
DD-WRT Guru


Joined: 31 Jan 2015
Posts: 5339
Location: Texas

PostPosted: Mon Jul 18, 2016 18:55    Post subject: Reply with quote
seems like a mess ---

reason I mentioned trying last working firmware -
meaning last firmware you could communicate with router

if erased kernel there still could be nvram settings that could cause you problems

sometimes this is fixed by TFTP the exact build used before any trouble started ... done it many times.

but looks like you may need to get inside with a cable Sad
groupie
DD-WRT Novice


Joined: 09 Aug 2014
Posts: 24

PostPosted: Mon Jul 18, 2016 19:17    Post subject: Reply with quote
the last version was "Step 2 - wndr3800-webflash29440(April-11-2016).bin". that's the one I connected with Telnet and "erase Linux".

tried re-flashing that one too.
groupie
DD-WRT Novice


Joined: 09 Aug 2014
Posts: 24

PostPosted: Tue Jul 19, 2016 0:24    Post subject: Reply with quote
got a USB to TTL adapter. the instructions,

http://inarea51.com/dd-wrt/builds/wndr3800ch/wndr3800chwebsite/


say to do this:

1. unplug power from router

2. make sure router power button is OFF

3. open router casing. connect USB-TTL adapter to J1.

(then plug USB into computer)

4. press router power button ON

5. open PUTTY session on COM3 at 115200,8,N,1

(actually during driver installation Windows had assigned it to COM4, said COM3 is in use already. so told PUTTY to use COM4)

6. "You should see U-Boot is running (Boot Looping) And USB Light Stays on and Green Power. It loops because the router has not been powered on"


didn't see anything. PUTTY session window just had a green, unblinking cursor. the router's power light didn't come on either. this is what happens:

with power OFF, plug in USB, get solid green USB light, solid amber 3 and 4 ethernet lights.
turn ON, all lights turn off.
turn back OFF, solid green usb light.

(power light never does not come on)

starting a PUTTY session at any time does not give anything but a green cursor.

double checked the TTL connection, got the right wires black/green/white/red connected to the right pins.
Malachi
DD-WRT Guru


Joined: 17 Jul 2012
Posts: 7221
Location: Columbus, Ohio

PostPosted: Tue Jul 19, 2016 1:46    Post subject: Reply with quote
Google dd-wrt serial recovery. You only use black for ground and tx and rx.
Only 3 wires get connected , none to vcc.
Don't power on the router till you have the serial cable connected to the router and putty is running.
To make sure you have a good cable, touch the tx and rx wires together and hit a few keystrokes on the keyboard. If it's good, you should see those keystrokes in the putty screen.

Look at these instructions also. Keep in mind the wndr3800 is basically a wndr3700 v2.
https://wiki.openwrt.org/toh/netgear/wndr3700#flashing_over_serial

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groupie
DD-WRT Novice


Joined: 09 Aug 2014
Posts: 24

PostPosted: Tue Jul 19, 2016 3:35    Post subject: Reply with quote
[didn't see the above post, got all this done without it]

finally got the PUTTY going, because someone said they only got theirs to work by plugging in the USB/TTL right after turning on the power to the router.

do that, and immediately start the PUTTY session, and you're in business.

that revealed that the hardware ID was corrupted. I was right, that's why it wouldn't take any firmware image.

in fact, this is a common problem. users reverting from dd-wrt back to stock Netgear firmware, often end up with a bricked router. they get the flashing green light just like I did... that is, in fact, the "waiting for firmware upgrade" mode. no button pressing necessary.

when they resolve the problem with TFTP, it's easy; when that doesn't work, just like me, no firmware will work at all and that's because all the parameters are corrupted, including hardware ID and board ID.

you have to set the hardware id AND the board id for the firmware to match. you get a clue when watching the PUTTY session, it shows the bad id's (############ or whatever) and shows the id's of the firmware you are trying to use. so set it to those.

mine was:

board_hw_id_set 29763654+16+128
board_model_id_set WNDR3800

that is easily resolved. however the rest of it is still corrupt and all the MAC addresses are FF-FF-FF-F-FF-FF, serial numbers and passwords are blank, etc. will most likely have software malfunctions and maybe hardware malfunction such as WiFi no work, buttons no work, etc.

need a good partition dump to overwrite that somehow. has been done but didn't say how and no partition dump can be found.

however that works, I would recommend getting a serial cable and glomming a copy of your own healthy partitions in case they get corrupted like this and you have to overwrite them.

getting the USB-TTL serial connection to work can be a problem. some people, like me, could not get it to work when following the directions. somebody else who didn't follow the directions found that it works when you do this:

1. power unplugged and router taken apart, connect GRND, TX, RX wires; do not connect VCC wire. that's what screwed up the procedure from working the most. leave that one off.

2. power switch OFF. power plugged in. USB unplugged. PUTTY ready to start session.

3. turn on router, quickly plug in USB, and start PUTTY session.

4. you will now get boot logging on the screen.

that's what worked for me. nothing else did.

you can leave PUTTY session running even though router is turned off, rebooting, etc. it simply waits for boot logging to continue.

during firmware update you can watch the progress on the PUTTY session window. first it erases memory, then writes to memory (two separate operations) that took around 2 minutes, not 5-10.

while doing that I observed the light to blink green while erasing, then blink orange/green while writing.

see attached .txt files for PUTTY session dump (how badly things are corrupted) and complete command reference.
groupie
DD-WRT Novice


Joined: 09 Aug 2014
Posts: 24

PostPosted: Tue Jul 19, 2016 3:40    Post subject: Reply with quote
now... does anybody know how to overwrite the partitions?
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